Take all (Leave nothing)
by Lady Horizon94
Summary: …Honestly, how could Sans even imagine that he would even consider Papyrus, when Sans walked in, looking like he was inviting Gaster? Sanster fic based on "I gave an inch, (You took a mile) by sweetsinnerchild WARNING: NON-CON Underfell AU
**A/N:** Hi! This fic is heavily based on Sweetsinnerchild's **I gave an inch, you took a mile** I would actually recommed to read it first. It's good shit 8D It can be found in here: /works/6164770/chapters/14124916 Oh, and yes, I did get permission from them. Basically it's about Gaster's point of view frpm two first chapters. I must say that english is not my native language and I can assure I can write better in my native language so if there are any weird words in a weird places or strange structures I apologize. **AND NOW WARNING: THIS STORY CONTAINS NON-CON, SEXUAL HARASHMENT AND MANIPULATION. IF YOU ARE UNCOMFORTABLE W/THIS OR THIS KIND OF STUFF TRIGGERS YOU DO. NOT. READ. THERE'S A REASON THIS STORY IS M RATED.**

And lastly, songs that inspired me while writing:

 **I know I'm a wolf by young heretics**

 **Little Red riding hood by Sam the sham and pharaohs**

 **Lasienkeli by Indica**

 **Varo by Indica**

 **Tag, you're it by Melanie Martinez**

 **She is my sin by Nightwish**

 **Leelee's vocal version of Ice from the ost of Puella Magic Madoka Magica!**

 **Take all (Leave nothing)**

They look so small and frail compared to Gaster. Looking up at him quivering in snow dust being stuck on their clothes… (Not that it really shows. Those rags are already filthy with dirt from dark caverns and streets they have wandered for all their lives)

In the corner of his eyes, the scientist can see wide, curious eyes staring at him like he was some kind of angel, a miracle, _a god._ It's disgusting and naïve and Gaster wants nothing more than dust this little brat and just watch as that hope would turn into a shock, hurt and betrayal. (But he doesn't, not yet at least)

Yes, this child does not spark his interest, doesn't wake up anything in him. The other skeleton on the other hand…

He is small yes, but he seems older. He's still exhausted from the ambush, sweat dripping from his forehead. Breathing coming out of him as heavy pants (Gaster notices how saggy shirt reveals his clavicle and how it raises and lowers with the rhythm of small skeleton's breathing. It's thin and white, completely unmarked)

His eyes are not as sickening pure as his little brother. They glare at him suspiciously and fearfully the other eye still glowing faintly blue, ready to attack if needed. And yet… they are soft, unusually so, and full of yearning of something a monster can never have in this world. That look is alluring, hypnotizing.

Gaster lifts his hand and rubs his jaw thinking, recalling how the older brother fought not too long ago in a battle he couldn't have possibly win on his own. Yet, he fought well despite his low HP and frail health. Also, his tactics and those bright eyes revealed his intelligence. It _just_ happens Gaster needs a new assistance. The old one was a blabbering, lazy fool not understanding the importance of experiments moving and hopping restlessly and loudly around.

Now the idiot was nothing but an ugly pile of dust in a bottom of a trashcan. _Perhaps…_

He offers him the job. Promises a safe place to sleep, enough food to eat. No harm to come for them. On only one condition: He does whatever Gaster tells him to do. The scientist extends his hand.

Older brother hesitates for a second, two seconds. Then, slowly, still wavering, as if making a deal with a devil himself, he raises his hand and takes Gaster's to accept his offer. (The man notices how elegant this young male's phalanges are, not very long, but very petite and graceful. They are warm: Almost feverish.)

Gaster catches small, restless movement in the corner of his eyes. The child looks back and forth from his big brother to the scientist and his face turns into a frown. Something dark flashes quickly in the boy's eyes and this both amuses and makes Gaster's curiosity peak up a bit. _Maybe baby brother is not as untainted as he thought_

"Sans – " The child starts with a weak, high-pitched voice which annoys the scientist's ears… _So his name is Sans…_ It sounds soft, something that would be easy to whisper in a darkness of a bedroom…

"I-It's alright Papyrus", Sans assures his brother a bit shakily offering a small, hesitant but relieved smile. "We're safe now. This man – "

"Gaster", The scientist tells him, not removing his gaze on Sans, ignoring Papyrus. He is most likely a burden after all, the only petty thing on this new and intriguing discovery.

Sans inhales. "Gaster", he repeats breathily. Gaster feels a sudden urge to hear his name from small skeleton's mouth. Stars, it feels like it is meant to say that way. "He is taking us to somewhere safe." However his voice is still doubtful, questioning.

Gaster doesn't say anything only tells them to follow him.

He grands his end of the bargain. He gives them their own living quarters – nothing fancy really. Truth to be told, there's not really enough room for two, but the way the little brother's eyes lit up, and jaw opens with wonder like this is the most miraculous thing he has ever seen and how Sans stands at the door as if he's about to do something he's not allowed to tells Gaster it's more than enough for these two. Finally, Papyrus smiles brightly like a sun itself – Gaster wants to smash his skull on the wall – running in the room, jumping on the bed.

"It's so soft, Sans!" He yells with all the childish excitement in his voice. Sans gives his brother a tired smile which doesn't quite reach his eyes.

"That's… good bro", Sans comments at least trying to take part of his brother's joy.

"I shall send clean clothes and food in here", Gaster comments and he can't resist as he puts his hand on Sans's shoulder if only for a moment. He feels petite bones, still flexible. An image of pearly, delicious whiteness curving just the right way flashes on his mind. Sans does not even seem to notice the touch being too overwhelmed with fatigue. Gaster lifts his hand and turns around to leave, not seeing any point of lingering there any longer. "Be in the lab at six in the morning. Be punctual." He doesn't wait and see if Sans nods or has anything to say.

The next morning Sans is there. Gaster is sitting on his chair, looking at a clipboard seemingly observing it. However, he hears the shy slow footsteps, yet there are spark and strength in them. Somehow, it's charming on its own way. Small, cold smile visits Gaster's face as he thinks what Sans might look like. Fearful, but full of amazement, curious gaze following other scientists pondering, where they are going and what are they doing – or no, that would be his _brother._ Who is most likely with Sans. Oh, the royal scientist can picture it all too well: Small sack of bones, whining and demanding, filled with silly, ridiculous thoughts _._ Sans probably looks around suspiciously, looking for any sort of threat.

"You're here", Gaster states turning finally around to look at the smaller skeleton, who _looks him straight in the eye._ There is uncertainty and fear, but he refuses to look away. This is… interesting, something new. It's more than a common occurrence that others avoid looking at him, thinking he's intimidating.

The scientist stands up, towering Sans easily. Gaster studies the other keeping his face expressionless and unreadable. He sees how the black, simple tank top he has chosen for the youngster shows the shapes of the ribs underneath. He wonders if Sans even knows how _sensitive_ they can be. He glances down and notices that pants are a bit too big and loose on him. They have slipped a bit _too_ down, revealing the curve of Sans's pelvis. There is a small, thin crack on it, but surprisingly enough, it only makes the bone look more appealing. _Makes Sans look more inviting._

And there is no Papyrus with him. At the same time, it's surprising and yet it isn't. Gaster has assumed that Sans doesn't like when his little brother is out of sight, then again, there are many dangerous things in the lab, which might accidently hurt careless, active child.

The smaller skeleton makes a small, restless movement. Gaster realizes he has been silent a very long moment. He turns around and starts walking. "Follow me."

And the other one does. The silence goes on, follows them and surrounds them. This doesn't bother the older male but he can practically feel Sans _squirm_ with stress and discomfort. "You didn't bring your brother with you?" He asks, not really invested getting an answer.

The footsteps behind him slow down a bit, but then speed up again. "Oh, He's… far too young. Can't read. He wouldn't be any help here." Gaster feels amused, so incredibly amused about that lie. He can see right through it. It's thrown too casually, too quickly with a shaky undertone. More importantly he knows exactly _what_ Sans fears and the whole idea is _utterly_ ridiculous.

He knows that some monsters can only find satisfaction in the purity of young children, they love to shatter it, show them the darkness of the world and leave them rot in their own, heavy misery.

…Gaster on the hand…

He does not like children. Nor finds beauty in their purity or innocence – it's sickening really – And he certainly does not find beauty in obnoxious, clingy little skeleton children.

However, He does find beauty in _small_ things. He finds it in _teasingly_ exposed peace of pelvic bone, in the elegant phalanges and in thin clavicle. He finds a strange mesmerizing allure in desperate, broken and sad eyes, which still contains softness in them. He finds beauty in things that are broken in just the right way but not entirely.

…Honestly, how could Sans even imagine that he would even _consider_ Papyrus, when Sans walked in, looking like he _was inviting Gaster?_

The scientist leads the smaller skeleton to a small locker room. There's a closet full of neatly folded lab coats and without saying a word, he tosses one to his new assistant.

The scientist learns quickly, that Sans is attractive in more way than one. He is silent, never getting in Gaster's way and does what he's told. And he's intelligent. Highly so. Already during first week Gaster catches Sans more than once reading his notes and studying his theories. And the scientist lets him. There's no harm in that and he's actually very satisfied – and impressed.

The only thing is… His self-control is hard to maintain. Gaster knows he's got Sans cornered. He has to obey his new boss and it wouldn't be hard to just bend Sans over to a desk and take him –

But Gaster wants more from Sans than just empty, one-time sex. Oh, he wants so much more. He wants to break Sans bit by bit, bend him, make the other skeleton his in every way possible until Sans has no other option than obey his every whim. To take and take until there's nothing left to take.

He needs to be patient. Sans is still too tense, too careful around him. Of course, no one is fully relaxed in the Underground but Gaster waits when Sans would be _used_ to soft blanked and having regular meals. When he can see how safe Papyrus is…

But oh, how the other makes it _so_ hard to wait… When something falls on the floor, and Sans bends down, Gaster can't help but look, look how the lab coat conforms the shapes of the bones, following the soft shape of the spine, dipping between his legs in a lewd way.

His many hands – which he often summons to help him with his works – twitch automatically acting on their master's will. _Patience,_ he tells himself. _You have time._

Unfortunately, he's not only one who has seen charm in his new assistant…

There are other scientists, of course. But Gaster is their ruler, what he says, goes and mostly other monsters leaves him alone, still recalling that poor monster's screams who dared to interrupt him in the middle of an extremely important experiment. So, when Sans just one day is there, working like he has always been part of the lab, no one asks questions.

But one of them notices the same things Gaster does. He's a bull monster, large and loud always filling the room with his ego and intolerable laugh. The man is brilliant yes, but Gaster has always been itching to just get rid of that inconvenience.

Those perverted and vile grins crosses the line. The monster has entered in a territory _which does not belong to him._

"Here's the damn report", The bull growls smacking a pile of papers on his boss's desk. The skeleton nods not even giving a glance towards the other. It's only when he starts to leave Gaster speaks.

"Sans is really… something, isn't he?" He let the words land between them, puts a hint of a thread in them. They linger in the air, between the two heavy and meaningful.

Of course, that fool doesn't catch the meaning. Doesn't understand the situation he's in. Instead, there's a chuckle full of desire. "Yeah, man I just wanna fuck that lil' guy's brains out!"

The next day, Sans is mopping the floor clean from the bull monster's dust after an experiment looking pale and about to vomit but doing so anyway. And across the room, Gaster can't help but smile.

Weeks go by and finally, _finally_ Sans's shoulders start to relax a bit. He does no longer flinch after hearing particularly loud scream. His steps are a bit lighter and he even starts to carry home small items that would interest him or Papyrus.

Sans hasn't gotten comfortable, but he's gotten used to his new environment, job and more importantly, Gaster. He's ripe to pick.

But this all must be started slowly. Partly, because Gaster wants the other one feel helpless, and out of control. Mostly, because Gaster enjoys a good chase, feeling of being in control. And when he will finally catches Sans…

 **He'll make sure to drown Sans in unwanted pleasure. Force Sans to enjoy every single moment.**

He starts with small. He let his hand linger on Sans phalanges, almost smiling as he feels Sans confusion. (He imagines how they would feel around his organ: Hesitating, quivering speeding up - )

When they're standing side by side, he lets his hand rest on Sans's cervical vertebrae, feeling his warm neck… (Oh, how he would ruin that white bone with dark markings)

Sometimes he lets his hand catch briefly on his vertebrae. (Sans shivers and Gaster can feel it through his hand.)

He expects the smaller one to say something, snap at him. Repeating the same old, worn out clishès 'Stop' or 'I don't want this'.

But he only stills, and the fear and panic on the other one's face only fuels Gaster's fantasies. He imagines Sans on his bed, that broken look on his face, legs spread open just for him…

He would take Sans _Y_ making him screaming his name, moan and pant. Perhaps the smaller skeleton would grab his shirt in an attempt to push him away but being so overtaken by pleasure he couldn't do anything else than cling on it.

Gaster hunger only grows and he can control himself less and less, his touches getting more impatient and demanding. Until one day, he can't wait any longer and has Sans cornered against a wall, digging his fingers on the jut of Sans's hip and rubbing the small of his back: He forces his leg against Sans' pelvis. And finally, his little prey has enough, as he slaps Gaster's hand away yelling him to stop.

The scientist is amused. Sans is trying to look angry and hateful but in all honestly manages only to look like small, barking dog. No matter how straight the skeleton is trying to stand, no matter how he glares, Gaster still towers him, still looks down on him.

"And here I'd thought you would wait until we were both naked", the scientist says calmly. He has been waited for this, after all, it's fun to watch how the smaller one would struggle against the web Gaster has weaved for him.

Sans's anger and fear are fighting for dominance in his face and oh, Gaster sees how his legs are tense, ready to run away any minute, can practically see wheels turning inside his assistant mind as he tries look any route of escape. (There isn't one)

"I'm not your personal whore", Sans snaps venom dripping from his voice, all the bottled up disgust attacking his boss.

It's the best joke Gaster has heard in ages. He laughs, _because_ _Sans is his. His whore, his pet, his_ _ **doll.**_

"You're supposed to do everything I tell you to", He explains as if Sans was a child. He can't help but grin, wide and predatory as he already undresses Sans in his mind. "Everything, including being 'my personal whore.'" Gaster reaches the male in front of him intoxicating lust hazing his mind –

Suddenly, there's a heavy weight on his soul and he's slammed on the cold hard floor. Sans's rapid footsteps echoing in the lab.

It takes a moment for Gaster to react, his irritation growing inside him. _How_ _ **dare**_ _he? Well, no matter, two can play the same game._ He slams the other on the floor with his magic hearing a sweet cry of desperation and disappointment.

The scientist takes his time as he stands up and wipes his shoulders clean. There's no rush. After all, his little pet can't run now. He can't help but feel annoyed for his own miscalculation. He should have break Sans more, force him to see the situation he's in…

Or maybe Sans isn't simply as sharp as he originally thought. It doesn't matter either way, **_Gaster has him now._** He stalks towards the other, never removing his gaze. Even now, the smaller skeleton looks wonderful, delicious even, lying on his stomach on the cold floor.

"That was the most stupid thing you could have done in your life", Gaster states calmly watching Sans shiver in useless rage. "You're usually so smart Sans, you had potential and that was why I saved you and your brother. But attacking me? Perhaps I misjudged your intelligence."

Sans tries to get up, but the scientist has none of that. He presses his food against the smaller one's back sharply, in a moment of anger and Sans's cry is like the most sweetest music to him.

However, he must not be _too_ harsh now. After all, this was expected and while Sans is not exactly a child, he is still young and maybe he hasn't learned all of the grim lessons Underground has to offer. And isn't Sans lucky to have a just the right man to guide him?

He offers a second chance. Sans tells him to just kill him. Gaster smiles a bit. Now that wouldn't do. "Kill you? Why would I do that?" He caresses his doll's skull feeling smooth bone against his phalanges "You're more useful alive to me."

"I'm not letting you to fuck me", Sans spats bitterly. Oh, he truly thinks he has a choice doesn't he? Thinking there's still a way out of this and yet… He's tiny on the floor not a long ago crushed under Gaster's foot.

Gaster tells him what would happen if Sans disobeyed him. How he would get what he wants anyway, that it's not about if Sans lets him or not.

"I'll be in my quarters. Think about it, won't you?" He releases Sans and walks away.

Shadows are getting longer, creeping against the walls as if they are trying to find their way out. Gaster pays no mind to darkness as he waits for Sans already feeling arousal growing, growling hungrily inside him. He's almost certain his assistant will come. That he's not fool enough to run. (But Gaster has taken that on accord, of course and he would get both of the skeleton brothers back just by snapping his fingers)

When there's a silent, wavering knock on the door the scientist smiles slyly, knowing he has caused the first crack on Sans' soul, taken the first step of owning him. He tells the other one to enter.

And oh, Sans is much better than he has expected. The way he is exposed in front of him, pulsing against his own fingers trying not to get a sound slip past his mouth, fighting against the growing pleasure. ( _Don't fight it doll, it feels so good, doesn't it? Oh, I can make you feel_ _ **even better my doll.**_ _)_

Sans's taste is sweet, it pours in his mouth like a nectar. He is so wet, already dripping for Gaster and he still tries to deny this, tries to escape the older male's exploring tongue and wiggle away.

There's defiance, yes. But all it takes is a small reminder and it crumbles into little pieces and Sans submits.

And oh stars, _he is so tight_ squeezing around Gaster, so adorable looking as he looks the scientist mouth half open, spine arching and curving elegantly shuddering under his boss's caresses. The name comes out of the smaller one with breathy pants and moans and the scientist pulls Sans even closer feeling almost feverish watching his little companion losing his composure completely.

The sweetest thing is however, how the little brat sees everything. Oh, the scientist has known from the beginning, has felt that possessive glare. He can't help but to look straight at Papyrus, smiling at him. _How could that little fool ever imagine he had a chance?_ Gaster bites Sans, leaving a mark. Making clear who is the one that has won, before closing the door as he buries himself even deeper into his possession.

Sans comes twice that night. Or rather, Gaster forces him to. Poor boy tries to hold back offering Gaster a challenge, the scientist smirks, reaching down to that little sensitive nub caressing and rubbing it – and Sans cries out when he just can't take it anymore.

When it's all over, dullness spreads to Sans's eyes and he refuses to look at the scientist. He stands up, come still dripping from him as he collects his clothes from the floor. Gaster frowns and the hands floating in the air grab his new doll forcing him to turn around.

"What do you think you're doing?" He asks calmly, but coldly. Sans doesn't look at him, his eyes gleam with tears he refuses to shed.

"I gave you what you wanted, sir. Now I'm going back to my brother", his voice is robotic and tight. He stands still, not even trying to fight against the hands holding him still.

Gaster chuckles, cruelly and mockingly. How charmingly enchantingly _naive_ of Sans. "Oh, but that's not all what I want from you Sans… Besides, you must be exhausted, why not sleep here?" He pats the empty spots of his bed and he takes the great pleasure as _the_ _doll_ starts to shake uncontrollable, his bones rattling. A few tears starting to escape his eye sockets.

"Please… No more…" He pleads eyes wide. Gasters smile is a charade of gentle as he walks towards Sans, stopping just in front of him. He kisses the other one's forehead taking his pet in his arms but the hands still stays in the air.

He carries him on the bed setting him lay on the side. Gaster himself spoons Sans, caging him in embrace. The man starts to pet his new doll slowly, smiling cruelly. He runs his phalanges along the straighten, tense spine, going up to Sans shoulder plate, rubbing it almost in a soothing manner. Sans does not relax, does not stop trembling. The scientist can almost taste his terrified confusion and this is almost more satisfying than the long chase or the sexual pleasure.

True it would be… wonderful to fill long night hours ravishing Sans, listening the soiree of his moans and cries. But this serves Gasters goals better. He can feel the doll break more and more with every caress, darkness squirming deeper and deeper in Sans's soul. The man can hardly wait when Sans's is nothing but submissive obedience depending on him in every way. Maybe then, Gaster can throw Papyrus back to streets where he belongs when his pet cannot even remember the word "no".

Quiet sobs breaks the silence and Gaster nuzzles closer, burying his face on Sans shoulder, kissing it gently, shushing him.

At this, the smaller one's breath comes out rapid, quick, startled pants. "W-why…?" He whispers desperately. "T-there's red light district in Capitol… I don't understand – "

The scientist turns Sans around studying his tear stained face. If fear has been reflected on that face these past weeks now it's twisted with pure raw horror and Gaster is pleased. Sans is so utterly, absolutely _beautiful like this._

Gaster is man of logic and coldness. However, he has his weakness and he takes liking on beautiful, extraordinary things. He does not actively collect them, but he finds them time to time… One of them is floating, blue kimono with butterfly print. He found it long ago in the dump, all broken and dirty. Honestly, the scientist does not know what made him pick it up and take it to be fixed in Capitol. But now, he's glad he did so. He can picture Sans in it, large sleeves sliding down the skeleton's arms when they are tied on the upwards. His leg spread, fabric folded around them and Sans's conjured organ, on a lewd display, dripping –

It would be beautiful combination of his two possibly most beautiful parts of his collections.

"It's true", Gaster finally answers putting his hand on that feverish cheek. "But I don't want just any whore. Why would I go there when I have you here?" He smiles, unkindly and menacing. "I don't think you quite see yourself the way I do." He whispers. "I've taken liking to you Sans, and I'm going to keep you – you're going to be my whore, my pet, my doll."

There's a flash of anger in Sans's eyes and for a moment he looks like he's going rise against his new master but then, he seems to remember Papyrus, remember he can't _afford_ any kind of resistance and he goes completely limb eyes dulling again.

Gaster smirks, letting his hands go lower and resting them on the back of Sans's pelvis.

And they both know: Gaster has won.

 **A/N: EDIT:** I fixed some mistakes I noticed after I posted this and changed a few words. (Also, can someone please call the cops on Gaster?)


End file.
